(a) Field of the Invention
The present invention relates to a liquid crystal display having wide viewing angle.
(b) Description of the Related Art
A liquid crystal display (LCD) includes two substrates and a liquid crystal layer interposed therebetween. The transmittance of the incident light is controlled by the strength of the electric field applied to the liquid crystal layer.
A vertically aligned twisted nematic (VATN) liquid crystal display has a couple of transparent substrates which have transparent electrodes respectively on their inner surfaces, a liquid crystal layer between two substrates and a couple of polarizers which are attached to the outer surfaces of the substrates respectively. In off state of the LCD, i.e., in the state that the electric field is not applied to the electrodes, the long axes of the liquid crystal molecules are perpendicular to the substrates. On the other hand, in on state of the LCD, i.e., in the state that the sufficient electric field is applied to the electrodes, the long axes of the liquid crystal molecules are parallel to the substrates and twisted spirally with a constant pitch from the inner surface of one substrate to that of the other substrate, and thus the orientation of the long axes of the liquid crystal molecules vary continuously.
The VATN LCD operating in normally black mode may have an off state which is sufficiently dark because the liquid crystal molecules are aligned perpendicular to the substrates in the off state. Therefore, the contrast ratio is relatively high compared with the conventional TN LCD. However, the viewing angle of the VATN LCD may not be so wide due to the difference between retardation values in various viewing directions.